...be made to produce 50-75fps more. On mine, the probe was sleeved with brass, an o-ring added, and a sleeve of brass on the probe tip (to push pellet in a little further). The transfer port sealed much better. The stock barrels are great if recrowned on both ends and use bushings to support the barrel fully. one in the front and one in the rear and one in the middle. My barrel and shroud has been shortened 1.5 inches as well.
With 10 pumps using a Crosman 14.3 grain pointed pellet the fps is an average of 632.
Next the piston will be made adjustable with a 1377/760 valve end. Would like to see how the larger valve does.
"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."